Dry-powder inhaler

ABSTRACT

An inhaler for delivering dry-powder medicament to a patient from an open blister pocket of a blister pack. The blister pack has a plurality of blister pockets spaced apart in a length direction of the pack and each containing a measured dose of the medicament. The inhaler includes a housing for enclosing used and unused portions of the blister pack together with a medicament dispensing mechanism for opening the blister pockets of the blister pack. The inhaler also includes a manifold through which air can be drawn in use of the inhaler, the manifold including an air inlet for receiving external air, at least one medicament aperture for communicating with an opened pocket of the blister pack to enable entrainment of the medicament by the air drawn through the manifold, and an air outlet for delivery of the entrained medicament to the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase of PCT Application No.PCT/EP2010/002993, filed May 17, 2010, which claims priority to U.S.Provisional Patent Application No. 61/179,167, filed May 18, 2009, bothof which are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

This invention relates to a dry-powder inhaler for delivering dry-powdermedicament doses to a patient. More particularly, the invention relatesto an inhaler of this type in which the medicament doses are stored in amedicament carrier in the form of a blister pack.

BACKGROUND OF THE INVENTION

Inhalers for delivering medicament to a patient by inhalation are known.Such devices include metered dose inhalers and dry-powder inhalers.

Metered-dose inhalers typically comprise a vessel, said vesselcontaining at least a pressurised propellant and a medicament, and ametering valve and some form of actuator for dispensing doses of theliquid medicament as an aerosol. In contrast, dry-powder inhalerscomprise a supply of dry-powder medicament together with means foraerosoling and deagglomerating the medicament into a form suitable fordelivery to a patient.

Dry-powder inhalers are generally considered to be easier to use thanmetered-dose inhalers because of difficulties in coordinating actuationof the metering valve of the metered-dose inhaler with a patent'sinspiration. Moreover, since the medicament is aerosolised and deliveredusing the patient's inspirational airflow, dry-powder inhalers do notrequire a propellant.

It has been recognised that, in order to aerosolise and deliver aconsistent dose of dry-powder medicament in an effective manner, themoisture content of the medicament must be carefully controlled. Indry-powder inhalers this can be conveniently achieved by storing dosesof the medicament in the blisters of a sealed blister pack. In use ofsuch devices, a dose of the medicament is typically liberated bypiercing, bursting or peeling off a portion of a cover sheet of theblister pack immediately before the dose is to be delivered to thepatient for inhalation.

A known dry-powder inhaler of this type, in which doses of themedicament are stored in a blister pack, is disclosed in U.S. Pat. No.5,590,645. The blister pack of this inhaler is formed as a flexibleelongate strip, and comprises a base sheet having a plurality ofrecesses spaced along its length and a cover sheet hermetically butpeelably sealed to the base sheet to define a plurality of blisterpockets each containing an identical dose of the medicament.

The inhaler of U.S. Pat. No. 5,590,645 comprises a medicament dispensingmechanism which is arranged to peel a portion of the cover sheet awayfrom the base sheet of the blister pack to thereby open a blister pocketeach time the inhaler is actuated. The mechanism includes a blister packindexing means for moving the opened pocket into registration withmedicament holes formed in a manifold of the inhaler, the manifold beingin fluid communication with a mouthpiece through which the patient caninhale. An unused portion of the blister pack and used potions of thebase sheet and cover sheet are stored within the body of the inhaler.

In use of the above-described inhaler, the patient exposes themouthpiece by rotating a cover relative to the body of the inhaler, andoperates a trigger to actuate the medicament dispensing mechanism. Thepatient then inhales through the mouthpiece to draw air through themanifold from within the body of the inhaler. The airflow passingthrough the mouthpiece and the manifold entrains the dry-powdermedicament contained within the opened blister pocket, which medicamentis delivered to the patient in aerosolised form. The trigger and thecover of the inhaler are then returned to their original positions toreset the medicament dispensing mechanism in preparation for asubsequent use.

Although dry-powder inhalers of the type disclosed in U.S. Pat. No.5,590,645 exhibit improved consistency in the size of the doses whichare delivered to the patient, there remains a need for inhalers havingimproved dosing consistency. There is a particular need for inhalers inwhich the risk of over-dosing can be minimised.

SUMMARY OF THE INVENTION

According to the invention there is provided an inhaler for deliveringdry-powder medicament to a patient from an open blister pocket of ablister pack, the blister pack having a plurality of blister pocketsspaced apart in a length direction of the pack and each containing ameasured dose of the medicament, the inhaler comprising:

-   -   a housing for enclosing used and unused portions of the blister        pack together with a medicament dispensing mechanism for opening        the blister pockets of the blister pack; and    -   a manifold through which air can be drawn in use of the inhaler,        the manifold comprising an air inlet for receiving external air,        at least one medicament aperture for communicating with an        opened pocket of the blister pack to enable entrainment of the        medicament by the air drawn through the manifold, and an air        outlet for delivery of the entrained medicament to the patient,    -   wherein the manifold and a part of the housing are provided as a        unitary moulded plastics component, and wherein the unitary        component defines, in use, at least a portion of the outer        surface of the inhaler in which the air inlet is arranged.

By providing the manifold having the air inlet and the part of thehousing which defines an outer surface of the inhaler (in which the airinlet is arranged) as a unitary component, the risk of air being drawninto the manifold from within the inhaler housing can be minimised. Itis desirable to avoid air from within the housing from being drawn intothe manifold because such air may entrain loose medicament in thehousing left over from previous actuations of the medicament dispensingmechanism, for example medicament which has not been inhaled or has beenincompletely inhaled.

Preferably, the air inlet of the manifold defines the sole point forentry for external air into the inhaler, and/or the manifold is arrangedsuch that, in use, air is drawn into the manifold solely through the airinlet, that is to say air is not drawn through any component of theinhaler other that the unitary component (and of course an openedblister pocket of the blister pack).

The unitary component defines, in use, at least a part of the outersurface of the inhaler surrounding the air inlet of the manifold, andmay in fact define the entire outer surface of the inhaler surroundingthe air inlet. In other embodiments, the outer surface surrounding theair inlet may in part be defined by other components such as covers,mouthpiece cover and mouthpiece inserts, etc.

The air inlet of the manifold may have an elongate cross-sectionalshape, and the cross-sectional area of the manifold may reduce in theairflow direction. With such an arrangement the airflow velocity withinthe manifold is lowest at the air opening, and this may reduce the riskof loose powder or other contaminants being entrained around the airinlet.

The manifold may comprise at least two medicament apertures arrangedsequentially in the airflow direction of the manifold, namely a firstmedicament aperture for the flow of air from the manifold into theopened blister pocket and a second medicament aperture for the flow ofthe entrained medicament from the opened blister pocket into themanifold. In this case, the geometry of the manifold may be specificallyadapted to direct air from the air inlet into the opened blister pocketthrough the first medicament aperture and to direct the entrainedmedicament from the opened blister pocket into the manifold through thesecond medicament aperture.

The geometry of the manifold may be adapted to provide the requiredflows by providing means for restricting airflow in the manifold betweenthe first and second medicament apertures, for example by providing alocalised reduction in the cross-sectional area of the manifold. Such alocalised reduction in the cross-sectional area of the manifold may takethe form of a protrusion in a wall of the manifold opposite to themedicament holes.

The unitary component may further define a mouthpiece arranged toreceive, in use, the entrained medicament from the air outlet of themanifold. An end of the mouthpiece may be provided with a mouthpiececover or insert having a surface around which a patient may comfortablyseal his lips.

The manifold and the mouthpiece may be arranged such that the airflowdirection in the mouthpiece is substantially perpendicular to theairflow direction in the manifold, with a bend in the airflow locatedadjacent to the second medicament aperture such that entrainedmedicament can be delivered to the patient from the opened blisterpocket along a substantially straight path.

The cross-sectional area of the mouthpiece may increase in the airflowdirection, and tapered walls of the mouthpiece may be provided with aplurality of airflow diversion holes. The airflow diversion holes arepreferably in fluid communication with the manifold such that, in use,air from the manifold is drawn through the airflow diversion holes. Theairflow diversion holes may be arranged such that, in use, air is drawnthrough the holes in a direction substantially parallel to a centralaxis of the mouthpiece (an acute angle to the walls of the mouthpiece)for preventing excessive transverse spreading of the entrainedmedicament in the mouthpiece.

The at least one medicament aperture may provided with at least oneobstacle to promote de-agglomerating the entrained medicament. Theobstacle may, in effect, serve as a divider to divide each aperture intoa plurality of sub-apertures. In use, agglomerated particles ofmedicament collide with the divider which leads to their break-up.

In embodiments, the unitary component is a moulded component, and may beformed of a plastics material. Suitable materials for the unitarycomponent may be selected from the group consisting of polyolefins,including polyethylene, in particular high density polyethylene (HDPE),and polypropylene; polyesters, including polyethylene terephthalate;polyamides, including nylons; thermosetting polymers, includingurea-formaldehyde, melamine, epoxy resins and polyimides; and mixturesor copolymers thereof.

The inhaler housing may comprise a pair of outer housing membersdefining an outer shape of the inhaler. One of these pair of outerhousing members may be the unitary component described above.

The inhaler may further comprise a dose counter, wherein the dosecounter comprises:

-   -   a display aperture formed in one of the pair of outer housing        members;    -   a display element having dose counting indicia, the display        element being rotatably mounted inside the housing such that a        succession of the dose counting indicia are sequentially visible        through the display aperture as the display element is rotated        about an axis of the outer shape of the inhaler; and    -   a driving means for incrementally rotating the display element        in response to actuation of the medicament dispensing mechanism.

Such a dose counter may enable a patient to reliably determine how manytimes the medicament dispensing mechanism has been actuated, which canhelp to avoid over-dosing or the inhalation of multiple doses.

The display aperture formed in the outer housing member may be providedwith a magnifying lens arranged to magnify the dose counting indicia ofthe display element. In this way, information from the dose counter maybe more easily seen by a patient and/or a greater number of indicia maybe provided. The magnifying lens may be a convex lens formed, forexample, from a transparent plastics material.

As the dose counting indicia of the display element are magnified, theiractual size may be relatively small, so that the display element can beprovided with a large number of indicia, and such that only one displayelement may be needed. In this case, complicated mechanisms for couplingmultiple rotatably mounted display elements can be avoided.

The dose counting indicia of the display element may include a uniqueindicium for display after each and every actuation of the medicamentdispensing mechanism. At least 10, preferably at least 20, morepreferably at least 50, even more preferably at least 60, unique dosecounting indicia may be provided, and the indicia may comprise numerals,preferably Arabic numerals. Each dose counting indicium may berepresentative of a number of doses dispensed by or remaining in theinhaler.

In embodiments, the inhaler housing further comprises an inner housingmember arranged within the pair of outer housing members describedabove.

In embodiments, the inhaler may further comprise the medicamentdispensing mechanism for opening the blister pockets of the blisterpack. This mechanism may form a part of a replaceable cartridgeinsertable into the inhaler housing, or the mechanism may be a fixed andpermanent part of the inhaler.

Embodiments of the inhaler may be suitable for delivering medicamentfrom a blister pack in the form of a flexible elongate strip comprisinga base sheet having a plurality of recesses spaced along its length anda cover sheet peelably sealed to the base sheet to define the pluralityof blister pockets. In this case, the medicament dispensing mechanism ofthe inhaler comprises means for peeling the cover sheet away from thebase sheet of the blister pack. A peeling-type mechanism may bepreferred to piercing or bursting-type mechanisms because it may providean inhaler which delivers greater dosing consistency.

The medicament dispensing mechanism may comprise a driven cover sheetwinding wheel for winding up and applying a tension to the used portionof the cover sheet and a guide surface for guiding the cover sheet ofthe unused portion of the blister pack. In this case, an end of theguide surface is arranged adjacent to an outer side surface of themanifold and defines a peeling edge. In use of the inhaler, the coversheet is peeled away from the base sheet at the peeling edge and theused portion of the cover sheet is passed between the peeling edge andthe outer side surface of the manifold, with an opened blister pocketmoving into registration with the at least one medicament aperture ofthe manifold.

In embodiments, the guide surface is defined by the inner housingmember, such that the manifold and the guide surface are defined byseparate components of the inhaler. Preferably, in use the outer sidesurface of the manifold splits the base sheet from the cover sheet.

During assembly of the inhaler, the used portion of the cover sheet isthreaded through a gap between the peeling edge and the side surface ofthe manifold and then engaged with the cover sheet winding wheel. Byproviding an inhaler in which the guide surface and the manifold aredefined by separate components, the width of the gap between the peelingedge and the manifold in the assembled inhaler can be minimised. Forexample, the used portion of the cover sheet may be threaded through thegap prior to assembly of the components and while the gap is relativelywide, and then the components may be assembled with the blister packinto the inhaler with the gap having a reduced width, for example onlymarginally wider than the thickness of the cover sheet. Typically, inuse, the outer side surface of the manifold and the peeling edge arearranged so as to define a gap sufficient to enable the cover sheet topass therethrough, said gap being less than or equal to about 1 mm,preferably less than or equal to about 0.8 mm, more preferably less thanor equal to about 0.4 mm. Preferably, said gap is from about 0.1 mm toabout 0.8 mm, preferably from about 0.2 mm to about 0.6 mm, morepreferably from about 0.2 to about 0.4 mm. Preferably, said gap is lessthan half the individual width of the recesses in the base sheet, morepreferably less than a quarter of the individual width of the recessesin the base sheet and even more preferably less than one eighth of theindividual width of the recesses in the base sheet. By minimising thewidth of the gap, the risk of medicament being lost from an openedblister pocket during use of the inhaler, as the blister pocket is movedfrom the peeling edge into registration with the at least one medicamenthole of the manifold, is minimised. In this way, underdosing (andpossible subsequent overdosing) may be avoided, the likelihood of thedevice jamming is also reduced and the device may be tuned so as toaccommodate different formulation characteristics more easily.

In embodiments, the inner housing member and the pair of outer housingmembers may comprise means for locating the inner housing memberrelative to the pair of outer housing members. The means for locatingmay include engagement tabs and recesses formed in the inner housingmember and the pair of outer housing members, the engagement tabs andrecesses being arranged to engage with each other to fix the location ofthe inner housing member relative to the pair of outer housing members.

In embodiments, the inner housing member may define internal transversewalls extending in the width direction of the blister pack for isolatingthe used portion of the cover sheet from the unused portion of theblister pack. Since the used portion of the cover sheet may carry aresidual amount of medicament left over from previous actuations of themedicament dispensing mechanism, the risk of overdosing can be reducedby isolating the used cover sheet from the unused portion of the blisterpack.

By “isolating”, it is meant that the internal transverse walls serve tomake it more difficult for medicament from the used portion of the coversheet to contaminate the unused portion of the blister pack.

The medicament dispensing mechanism may further comprise a driven basesheet winding wheel for winding up the used portion of the base sheet,and the inner housing member may further define internal transversewalls extending in the width direction of the blister pack for isolatingthe used portion of the base sheet from the unused portion of theblister pack. Like the used portion of the covers sheet, the usedportion of the base sheet may also carry residual medicament and it istherefore advantageous to isolate this from the unused portion of theblister pack.

The internal transverse walls of the inner housing member may defineseparate compartments for accommodating the used portion of the coversheet and the used portion of the base sheet, the separate compartmentsbeing arranged to contain loose medicament, that is to say prevent loosemedicament from contaminating the unused portion of the blister pack.The internal transverse walls of the inner housing member may furtherdefine a separate compartment for accommodating the unused portion ofthe blister pack. Surfaces of the inner housing member and one of thepair of outer housing members may be arranged to substantially enclosethe unused portion of the blister pack.

The internal transverse walls may extend in a perpendicular directionfrom a base surface of the inner housing member, the base surface of theinner housing member being arranged to support a side edge of the unusedportion of the blister pack, which unused portion may be coiled up. Oneof the pair of outer housing members may be arranged to support anopposite side edge of the unused portion of the blister pack.

In embodiments, the medicament dispensing mechanism may comprise meansfor longitudinally indexing the blister pack in response to eachactuation of the medicament dispensing mechanism, the blister pack beingindexed by a distance equal to the pitch between blister pockets, suchthat each actuation causes a blister to be brought into registrationwith the at least one medicament apertures of the manifold. The meansfor indexing may comprise a driven indexing wheel having recessesadapted to receive the base sheet of the blister pack, the recessedwheel being arranged to turn by a predetermined angle in response toeach actuation of the medicament dispensing mechanism. The indexingwheel may be arranged to face the guide surface of the medicamentdispensing mechanism.

The inhaler may comprise a trigger control for actuating the medicamentdispensing mechanism and/or a cover rotatable between an open positionin which the inhaler can be used and a closed position in which theinhaler cannot be used.

Other features and/or advantages of the invention will be apparent fromdetailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

A specific embodiment of the invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a known blister pack for use with adry-powder inhaler;

FIG. 2 is an exploded view of a known dry-powder inhaler comprising theblister pack shown in FIG. 1;

FIG. 3 is a cross-sectional plan view of the dry-powder inhaler shown inFIG. 1 for use in explaining the principle of operation;

FIG. 4 is an exploded view of a dry-powder inhaler according to theinvention, with some components of the inhaler omitted for clarity;

FIG. 5 is a cross-sectional plan view of the dry-powder inhaler shown inFIG. 4 for use in explaining the principle of operation;

FIGS. 6 and 7 are different perspective views of an outer housing memberof the dry-powder inhaler shown in FIG. 4;

FIG. 8 is an enlarged fragment of a cross-sectional side view of theouter housing member shown in FIGS. 6 and 7;

FIG. 9 is a front view of the outer housing member shown in FIGS. 6 and7;

FIG. 10 is an enlarged fragment of a cross-sectional plan view of theouter housing member shown in FIGS. 6 and 7; and

FIG. 11 is a perspective view of certain components of the dry-powderinhaler shown in FIG. 4 for use in explaining its method of assembly.

DETAILED DESCRIPTION

The invention provides an inhaler for delivering dry-powder medicamentto a patient from an open blister pocket of a blister pack. The blisterpack has a plurality of blister pockets spaced apart in a lengthdirection of the pack and each contains a measured dose of themedicament. Thee inhaler comprises a housing for enclosing used andunused portions of the blister pack together with a medicamentdispensing mechanism for opening the blister pockets of the blisterpack. The inhaler also comprises a manifold through which air can bedrawn in use of the inhaler. The manifold comprises an air inlet forreceiving external air, at least one medicament aperture forcommunicating with an opened pocket of the blister pack to enableentrainment of the medicament by the air drawn through the manifold, andan air outlet for delivery of the entrained medicament to the patient.According to the invention, the manifold and a part of the housing areprovided as a unitary moulded plastics component which defines, in useof the inhaler, at least a portion of the outer surface of the inhalerin which the air inlet is arranged.

FIG. 1 shows a known blister pack 1 which is suitable for use with knowndry-powder inhalers and dry-powder inhalers according to the invention.The blister pack 1 is in the form of a flexible elongate strip defininga single row of blister pockets 3 spaced along its length. The blisterpack 1 may have, for example, sixty or one hundred blister pockets intotal.

The blister pack 1 comprises a base sheet 5 in which recesses eachcorresponding to a blister pocket 3 are formed and a cover sheet 7 whichis hermetically but peelably sealed to the surface of the base sheet 5surrounding the recesses. The base sheet 5 and the cover sheet 7 aretypically formed of laminates comprising plastics and aluminium films.The base sheet 5 is more rigid than the cover sheet 7, and preferablyhas a rigidity which is sufficient to maintain a predetermined shape ofeach formed recess. The recesses formed in the base sheet 5 are elongatein shape, with a length direction corresponding to the width directionof the blister pack 1.

The cover sheet 7 is hermetically but peelably sealed to the base sheet5 by a heat seal lacquer. The cover sheet 7 is sealed to the base sheet5 over its entire surface except for those portions which overlie therecesses in the base sheet 5 and leading edge portions 9, 11 of the basesheet 5 and the cover sheet 7. As the blister pack 1 is used up, theleading edge portions 9, 11 of the base sheet 5 and the cover sheet 7lengthen, and these portions are described herein as “used portions”.The portion of the blister pack 1 of which the cover sheet 7 has notbeen peeled away from the base sheet 5 is described herein as the“unused portion”. The blister pack 1 is arranged such that the coversheet 7 can be peeled away from the base sheet 5 is a progressivemanner, so that the blister pockets 3 can be opened one at a time.

Each blister pocket 3 of the blister pack 1 comprises an enclosed volumedefined by surfaces of the base sheet 5 and the cover sheet 7. Theenclosed volume defined by the blisters is generally constant and isfilled with a predetermined quantity of dry-powder medicament suitablefor inhalation by a patient. In use of the blister pack 1, the leadingedge 11 of the cover sheet 7 is peeled away from the base sheet 5 toopen the blister pockets 3. The leading edge of the cover sheet 7 isprovided with a loop 13 for applying a tension to enable to cover sheet7 to be peeled away from the base sheet 5.

A more extensive description of the blister pack 1 can be found in U.S.Pat. No. 5,590,645, the entire content of which is incorporated hereinby reference.

FIGS. 2 and 3 show a known dry-powder inhaler 21 which comprises theblister pack 1 shown in FIG. 1. FIG. 2 is an exploded view of theinhaler 21 and FIG. 3 is a cross-sectional plan view of the inhaler 21for use in explaining its principle of operation.

The inhaler 21 has a disc-like outer shape with rounded edges and athickness sufficient to accommodate the width of the blister pack 1. Aswell as the blister pack 1, the inhaler 21 comprises a housing forenclosing used and unused portions of the blister pack 1, a medicamentdispensing mechanism for opening the blister pockets 3 of the blisterpack 1, a manifold through which air can be drawn in use of the inhaler21, and a dose counter for counting the number of doses dispensed by orremaining in the inhaler 21.

The inhaler housing comprises a pair of housing members, namely an upperhousing member 23 and a lower housing member 25, which snap-fit togetherto define a significant part of the outer surface of the inhaler 21. Theupper and lower housing members 23, 25 also define an internal chamber.The inhaler 21 is additionally provided with a cover 27 which ispivotally mounted to the housing members 23, 25 and is arranged torotate about the housing between open position of the inhaler 21, asshown in FIG. 3, and a closed position of the inhaler 21 (not shown).

The medicament dispensing mechanism of the inhaler 21 is largelycontained within the housing and essentially includes means for peelingthe cover sheet 7 from the base sheet 5 of the blister pack 1 to open ablister pocket 3, and means for indexing the longitudinal position ofthe blister pack 1 by a distance equal to the longitudinal pitch betweenblister pockets 3, so as to bring the newly opened blister pocket 3containing dry-powder medicament into alignment with the manifold(described below) to enable inhalation by the patient.

The medicament dispensing mechanism comprises a pivotally mountedtrigger 29 having a finger tab, a blister pack indexing wheel 31 mountedabout an indexing ratchet wheel 33, a base sheet winding wheel 35, acover sheet winding wheel 37 a, 37 b, and a guide surface 39 for guidingthe cover sheet-side of the blister pack 1. The guide surface 39 isdefined by a moulded plastics component 41 and includes a peeling edgefor separating the cover sheet 7 from the base sheet 5 of the blisterpack 1.

The mechanism also comprises a pawl 43 attached to the housing forengaging teeth of the base sheet winding wheel 35 to preventanticlockwise (backwards) rotation.

The cover sheet winding wheel 37 a, 37 b comprises a first part in theform of a toothed wheel 37 a having protruding axial and non-axialparallel shafts and a second part in the form of a wheel 37 b having ahollow shaft provided with resilient wings extending outwardly from theshaft. The protruding shaft of the wheel 37 a engages with the hollowshaft of the wheel 37 b such that one wheel cannot be rotated relativeto the other.

The manifold is defined by the same moulded plastics component 41 thatdefines the guide surface 39 of the medicament dispensing mechanism. Themanifold includes an air inlet 45 for receiving air from within thehousing, a medicament aperture 47 for communicating with the internalchamber defined by the housing and through which entrained medicament isdrawn, and an air outlet 49 for delivery of the entrained medicament tothe patient. The air outlet 49 is in communication with a mouthpieceprovided with a mouthpiece insert 51.

The dose counter of the inhaler comprises a display aperture 55 formedin the lower housing member 25 and a display element in the form of adisplay ring 53 provided with dose counting indicia and arranged suchthat a succession of the indicia are sequentially visible through thedisplay aperture as the display ring 53 is rotated about an axis of thedisc-like outer shape of the inhaler 21. An inner edge of the displayring 53 is provided with teeth for rotationally driving the display ring53.

The blister pack 1 is arranged within the inhaler 21 such that an unusedportion is loosely coiled within the internal chamber defined by thehousing. The leading edge of the cover sheet 7 is attached to thenon-axial shaft of the cover sheet winding wheel 37 a by its loop 13 andthe used portion of the cover sheet 7 is wound around the resilientwings of the cover sheet winding wheel 37 b. The used portion of thebase sheet 5 is loosely wound around the base sheet winding wheel 35.

The portion of the blister pack 1 at which the cover sheet 7 separatesfrom the base sheet 5 is arranged such that the recesses of the basesheet 5, which read through to the other side of the base sheet 5 asprotrusions, are received in circumferentially spaced recesses in thesurface of the indexing wheel 31. The recesses of the base sheet 5 aremaintained within the recesses of the indexing wheel 31 by the guidesurface 39 acting on the cover sheet-side of the blister pack 1. Theused portion of the base sheet 5 extends in front of the medicamentaperture 47 of the manifold in a direction towards the base sheetwinding wheel 35 and the used portion of the cover sheet 7 passesbetween the peeling edge of the guide surface 39 and the outer sidesurface of the manifold in a direction towards the cover sheet windingwheel 37 a, 37 b.

In use of the known inhaler 21, the patient moves the cover 27 to theopen position in which the mouthpiece insert 51 is exposed, as shown inFIG. 3. The patient then presses the finger tab of the trigger 29 torotate a set of teeth formed on an arcuate surface thereof. The teeth ofthe trigger 29 engage circumferential teeth formed on the indexingratchet wheel 33, rotation of which causes rotation of the indexingwheel 31. Rotation of the indexing wheel 31 also causes rotation of thebase sheet winding wheel 35, the lid sheet winding wheel 37 a, 37 b andthe display ring 53 of the dose counter.

The rotation of the cover sheet winding wheel 37 a, 37 b, applies atension to the used portion of the cover sheet 7 which is sufficient topeel a portion of the cover sheet 7 from the base sheet 5 of the blisterpack to thereby open a blister pocket 3 containing a dose of dry-powdermedicament. At the same time, the indexing wheel 31 is rotated by anangle sufficient to longitudinally index the blister pack 1 by adistance equal to the pitch between blister pockets 3 to thereby movethe opened blister pocket 3 into registration with the medicamentaperture 47 of the manifold.

The rotation of the display ring 53 of the dose counter causes a dosecounting indicium to be incremented, to thereby inform the patient thata dose has been dispensed.

The patient can then inhale the dose of dry-powder medicament byinhaling through the mouthpiece to draw air through the air inlet 45 ofthe manifold, which air passes through the medicament aperture 47 toentrain the medicament, and is delivered to the patient via the airoutlet 49.

After use of the inhaler 1, the cover 27 is rotated back the closedposition (not shown) to reset the medicament dispensing mechanism inpreparation for a subsequent use.

Inhalers of the type described above are described in more detail in theaforementioned U.S. Pat. No. 5,590,645.

The known inhaler described above is satisfactory in many respects. Inparticular, the use of a peelable blister pack enables the moisturecontent of the dry-powder medicament to be carefully controlled andthis, in combination with the peeling-type medicament dispensingmechanism provides consistent dose sizes. However, there remains a needfor an improved dry-powder inhaler.

FIGS. 4 to 11 show a dry-powder inhaler 101 according to the invention,which inhaler comprises the blister pack 1 shown in FIG. 1. FIG. 4 is anexploded view the inhaler 101, with some components of the inhaleromitted for clarity. FIG. 5 is a cross-sectional plan view of theinhaler 101. FIGS. 6 and 7 are different perspective views of an outerhousing member of the inhaler 101. FIG. 8 is an enlarged fragment of across-sectional side view of the outer housing member. FIG. 9 is a frontview of the outer housing member. FIG. 10 is an enlarged fragment of across-sectional plan view of the outer housing member. FIG. 11 is aperspective view of certain components of the inhaler 101.

The inhaler 101 according to the invention is similar in many respect tothe known inhaler 21 described above. Aspects of the inhaler 101 whichare not specifically described below should be taken to be the same orsimilar to those described above.

Accordingly, with specific reference to FIGS. 4 and 5, the inhaler 101according to the invention has an outer shape with rounded edges and athickness sufficient to accommodate the width of the blister pack 1. Theinhaler comprises the blister pack 1 described above, a housing forenclosing used and unused portions of the blister pack 1, a medicamentdispensing mechanism for opening the blister pockets 3 of the blisterpack 1, a manifold through which air can be drawn in use of the inhaler101, and a dose counter for counting the number of doses dispensed by orremaining in the inhaler 101.

The inhaler housing comprises a pair of outer housing members, namely anupper member 103 and a lower member 105 which snap-fit together todefine a significant part of the outer surface of the inhaler 101. Theupper and lower housing members 103, 105 also define an internalchamber. The inhaler 101 is additionally provided with a pivotablymounted cover 107 arranged to rotate about the housing between open andclosed positions.

The medicament dispensing mechanism of the inhaler 101 is largelycontained within the housing and includes means for peeling the coversheet 7 from the base sheet 5 of the blister pack 1 to open a blisterpocket 3, and means for indexing the longitudinal position of theblister pack 1.

More particularly, the medicament dispensing mechanism comprises apivotally mounted trigger 109 having a finger tab, a blister packindexing wheel 111, a base sheet winding wheel 113, a cover sheetwinding wheel 115, and a guide surface 117 for guiding the coversheet-side of the blister pack 1. The guide surface 117 includes apeeling edge 119 for separating the cover sheet 7 from the base sheet 5of the blister pack 1.

The dose counter of the inhaler 101 comprises a display aperture 121formed in the lower outer housing member 105 and a display element inthe form of a display ring 147 provided with dose counting indicia andarranged such that a succession of the indicia are sequentially visiblethrough the display aperture 121 as the display ring 147 is rotatedabout an axis of the outer shape of the inhaler 101. The dose countingindicia comprise Arabic numerals which count down from the numeral “60”to the numeral “0” in increments of one to indicate the number of dosesremaining in the inhaler 101.

An inner edge of the display ring 147 is provided with teeth forrotationally driving the display ring 147, which teeth are driven by agear train coupled to the medicament dispensing mechanism. The geartrain is arranged so that the indicium visible through the displayaperture 121 is incremented each time the medicament dispensingmechanism is actuated.

The display aperture 121 formed in the upper outer housing member 103 isprovided with a convex lens 123 which is spaced from the dose countingindicia of the display ring and arranged to magnify the indicia. Theconvex lens 123 is formed of a transparent plastics material.

By provided the convex lens 123, a patient may more easily observe thedose counting indicia of the dose counter and/or the need for multipledisplay rings may be avoided (since a larger number of small indicia canbe provided on a single ring).

With specific reference to FIGS. 6 to 10, the manifold of the inhaler101 includes an air inlet 125 for receiving external air, a pair ofmedicament apertures 127 a, 127 b for communicating with an openedpocket 3 of the blister pack to enable entrainment of medicament by airdrawn through the manifold and an air outlet 129 for delivery of themedicament to the patient. The air inlet 125 defines the sole point ofentry for external air into the inhaler 101.

According to the invention, the manifold is formed as part of the upperouter housing member 103. In other words, the manifold and the upperouter housing member 103 are formed as a unitary component, specificallya unitary moulded plastics component formed of high density polyethylene(HDPE).

In use of the inhaler 101 (that is to say with the cover 107 in the openposition), the unitary component defines the part of the outer surfaceof the inhaler 101 which surrounds the air inlet 125. In other words,the unitary component defines not only the manifold, but also an outersurface of the inhaler in which the air inlet 125 of the manifold isformed. Furthermore, air is drawn into the manifold solely through theair inlet (apart from the air which circulates through the medicamentapertures 127 a, 127 b).

By such an arrangement, the risk of drawing air into the manifold fromwithin the inhaler housing may be reduced. Such air may be contaminatedwith medicament left over from previous actuations of the medicamentdispensing mechanism.

The air inlet 125 of the manifold has an elongate, arcuate cross-sectionwhich reduces in length in the direction of the inhaled airflow. Themedicament apertures 127 a, 127 b are provided sequentially in theairflow direction, which direction is parallel to the axis of the outershape of the inhaler 101 and the width direction of the blister pack 1.A protrusion 131 in the wall of the manifold facing the medicamentapertures 127 a, 127 b is provided to restrict airflow in the manifoldbetween the medicament apertures 127 a, 127 b. In this way, air drawnthrough the manifold is directed from the air inlet 125 into an openedblister pocket 3 through the first medicament aperture 127 a, andentrained medicament is directed from the opened blister pocket 3 intothe manifold through the second medicament aperture 127 b.

The unitary component defining the manifold and the upper outer housingmember 103 also defines a mouthpiece 133 arranged to receive theentrained medicament from the air outlet 129 of the manifold. Themouthpiece 133 is arranged substantially perpendicular to the manifoldsuch that an axis of the mouthpiece 133 is aligned with the secondmedicament aperture 127 b. Tapered walls of the mouthpiece 133 areprovided with airflow diversion holes 135 a, 135 b which communicatewith the manifold and provide an alternative route for air drawn throughthe manifold, as illustrated by the arrows in FIG. 10. The airflowdiversion holes 135 a, 135 b are arranged such that air therefrom isdrawn into the mouthpiece in a direction substantially parallel to theaxis of the mouthpiece 133 for preventing excessive spreading of theentrained medicament.

Each of the medicament apertures 127 a, 127 b is provided with adivider. The dividers serve to deagglomerate the medicament by breakingup the medicament particles.

The mouthpiece 133 is provided with a mouthpiece insert 145 formed of asoft plastics material which provides a comfortable surface againstwhich the patient may seal his lips during use of the inhaler 101.

With reference again to FIGS. 4, 5 and 11, it will be seen that theinhaler 101 also comprises an inner housing member 137. The innerhousing member 137 is arranged within the outer housing members 103, 105and takes to form of a tray-like moulded plastics component having aflat base surface from which transverse walls extend in a directionperpendicular to the base surface (corresponding to the width directionof the blister pack 1). Apertures are provided in the base surface ofthe inner housing member 137 to enable the proper functioning ofelements of the medicament dispensing mechanism. The transverse wallsserve to isolate the used portions from the unused portion of theblister pack 1. Thus, a first transverse wall 139 separates the usedportion of the of the cover sheet 7 from the unused portion of theblister pack 1 and a second transverse wall 141 separates the usedportion of the base sheet 5 from the unused portion of the blister pack1.

The transverse walls of the inner housing member 137 in effect defineseparate compartments for accommodating the different portions of theblister pack 1, thereby minimising the risk that residual medicament onthe used portions of the base sheet 5 and the cover sheet 7 willcontaminate the unused portion of the blister pack 1, which could leadto overdosing.

The inner housing member 137 and the upper outer housing member 103together define an enclosure 143 which substantially encloses the unusedportion of the blister pack 1 to protect it from contamination byresidual medicament contained in the inhaler housing.

The inner housing member 137 described above also defines the guidesurface 117 of the medicament dispensing mechanism, that is to say theinner housing member 137 and the guide surface 117 are provided as aunitary component.

The blister pack 1 is arranged within the inhaler 101 such that anunused portion is loosely coiled within the enclosure 143 defined by thehousing members. The used portion of the cover sheet 7 is wound aroundthe cover sheet winding wheel 115. The used portion of the base sheet 5is loosely wound around the base sheet winding wheel 113.

The portion of the blister pack 1 at which the cover sheet 7 separatesfrom the base sheet 5 is arranged such that the recesses of the basesheet 5, which read through to the other side of the base sheet 5 asprotrusions, are received in circumferentially spaced recesses in thesurface of the indexing wheel 111. The recesses of the base sheet 5 aremaintained within the recesses of the indexing wheel 111 by the guidesurface 117 acting on the cover sheet-side of the blister pack 1. Theused portion of the base sheet 5 extends in front of the medicamentapertures 127 a, 127 b of the manifold in a direction towards the basesheet winding wheel 113. The used portion of the cover sheet 7 passesbetween the peeling edge 119 of the guide surface 117 and the outer sidesurface of the manifold in a direction towards the cover sheet windingwheel 115.

During assembly of the inhaler 101, the used portion of the cover sheet7 is threaded through a gap between the peeling edge 119 and the sidesurface of the manifold and then engaged with the cover sheet windingwheel 115. By providing an inhaler 101 in which the guide surface 117and the manifold are defined by separate components (namely the innerhousing member 137 and the upper outer housing member 103,respectively), the width of the gap between the peeling edge 119 and themanifold in the assembled inhaler can be minimised. In particular, theused portion of the cover sheet 7 may be threaded through the gap priorto assembly of the components 137, 103 and while the gap is relativelywide, and then the components 137, 103 may then be assembled with theblister pack 1 into the inhaler 101 with the gap having a reduced width,for example only marginally wider than the thickness of the cover sheet7. By minimising the width of the gap, the risk of medicament being lostfrom an opened blister pocket 3 during use of the inhaler 101, as theblister pocket 3 is moved from the peeling edge 119 into registrationwith the medicament holes 127 a, 127 b of the manifold, is minimised. Inthis way, underdosing (and possible subsequent overdosing) may beavoided.

The inner housing member 137 and the pair of outer housing members 103,105 comprise means for precisely locating the inner housing member 137relative to the pair of outer housing members 103, 105. The locatingmeans comprises engagement tabs and recesses (not shown) formed in theinner housing member 137 and the pair of outer housing members 103, 105,the engagement tabs and recesses being arranged to engage with eachother to fix the relative locations of the components.

In use of the inhaler 101 according to the invention, the patient movesthe cover 107 to the open position in which position the mouthpieceinsert 145 is exposed. The patient then presses the finger tab of thetrigger 109 to rotate a set of teeth formed on an arcuate surfacethereof. The teeth of the trigger 109 engage circumferential teethformed on an indexing ratchet wheel (not shown), rotation of whichcauses rotation of the indexing wheel 111. Rotation of the indexingwheel 111 also causes rotation of the base sheet winding wheel 113, thelid sheet winding wheel 115 and the display ring of the dose counter(not shown).

The rotation of the cover sheet winding wheel 115, applies a tension tothe used portion of the cover sheet 7 which is sufficient to peel aportion of the cover sheet 7 from the base sheet 5 of the blister packto thereby open a blister pocket 3 containing a dose of dry-powdermedicament. At the same time, the indexing wheel 111 is rotated by anangle sufficient to longitudinally index the blister pack 1 by adistance equal to the pitch between blister pockets 3 to thereby movethe opened blister pocket 3 into registration with the medicamentapertures 127 a, 127 b of the manifold.

The rotation of the display ring of the dose counter causes a dosecounting indicia to be incremented, to thereby inform the patient thatone dose has been dispensed.

The patient can then inhale the dose of dry-powder medicament byinhaling through the mouthpiece 133 to draw air through the air inlet125 of the manifold, which air passes through the medicament apertures127 a, 127 b to entrain the medicament, and is delivered via the airoutlet 129 and the mouthpiece 133.

After use of the inhaler 101, the cover 107 is rotated back the closedposition to reset the medicament dispensing mechanism in preparation fora subsequent use.

A specific embodiment of the invention has been described above indetail. Various changes to the embodiment may be made without departingfrom the scope of the invention, as defined by the claims.

The invention claimed is:
 1. An inhaler for delivering dry-powdermedicament to a patient from an open blister pocket of a blister pack,the blister pack having a plurality of blister pockets spaced apart in alength direction of the pack and each containing a measured dose of themedicament, the inhaler comprising: a housing for enclosing used andunused portions of the blister pack together with a medicamentdispensing mechanism for opening the blister pockets of the blisterpack; and a manifold through which air can be drawn in use of theinhaler, the manifold comprising an air inlet for receiving externalair, at least one medicament aperture for communicating with an openedpocket of the blister pack to enable entrainment of the medicament byair drawn through the manifold, and an air outlet for delivery of theentrained medicament to the patient, wherein the manifold and a part ofhe housing are provided as a unitary moulded plastics component, whereinthe unitary component defines, in use, at least a portion of he outersurface of the inhaler in which the air inlet is arranged, and whereinthe at least one medicament aperture is provided with at least oneobstacle for de-agglomerating the entrained medicament.
 2. An inhaleraccording to claim 1, wherein the manifold is arranged such that, inuse, air is drawn into the manifold solely through the air inlet.
 3. Aninhaler according to claim 1, wherein the air inlet of the manifolddefines a sole point for entry for external air into the inhaler.
 4. Aninhaler according to claim 1, wherein the air inlet of the manifold hasan elongate cross-sectional shape, and wherein the cross-sectional areaof the manifold reduces in the airflow direction.
 5. An inhaleraccording to claim 1, wherein the unitary component further defines amouthpiece arranged to receive, in use, the entrained medicament fromthe air outlet of the manifold.
 6. An inhaler according to claim 5,wherein the manifold and the mouthpiece are arranged such that theairflow direction in the mouthpiece is substantially perpendicular tothe airflow direction in the manifold and a bend in the airflow islocated adjacent to the at least one medicament aperture, such thatentrained medicament can be delivered to the patient from the openedblister pocket along a substantially straight path.
 7. An inhaleraccording to claim 5, wherein the cross-sectional area of the mouthpieceincreases in the airflow direction.
 8. An inhaler according to claim 1,wherein the unitary component is formed of a moulded plastics material.9. An inhaler according to claim 8, wherein the unitary component isformed of a material selected from the group consisting of polyolefins,including polyethylene, high density polyethylene (HDPE), andpolypropylene; polyesters, including polyethylene terephthalate;polyamides, including nylons; thermosetting polymers, includingurea-formaldehyde, melamine, epoxy resins and polyimides; and mixturesor copolymers thereof.
 10. An inhaler according to claim 1, furthercomprising a cover rotatable between an open position in which theinhaler can be used and a closed position in which the inhaler cannot beused.
 11. An inhaler according to claim 1, wherein the housing comprisesa pair of outer housing members defining an outer shape of the inhaler,and wherein one of the pair of outer housing members is the unitarycomponent.
 12. An inhaler according to claim 11, further comprising adose counter, wherein the dose counter comprises: a display apertureformed in one of the pair of outer housing members; a display elementhaving dose counting indicia, the display element being rotatablymounted inside the housing such that a succession of the dose countingindicia are sequentially visible through the display aperture as thedisplay element is rotated about an axis of the outer shape of theinhaler; and a driving means for incrementally rotating the displayelement in response to actuation of the medicament dispensing mechanism,wherein the display aperture formed in the outer housing member isprovided with a magnifying lens arranged to magnify the dose countingindicia of the display element.
 13. An inhaler according to claim 12,wherein the magnifying lens is a convex lens.
 14. An inhaler accordingto claim 12, wherein the magnifying lens is formed of a transparentplastics material.
 15. An inhaler according to claim 12, comprising nomore than one rotatably mounted display element having dose countingindicia.
 16. An inhaler according to claim 12, wherein the dose countingindicia of the display element include a unique indicium for displayafter each and every actuation of the medicament dispensing mechanism.17. An inhaler according to claim 12, wherein the dose counting indiciaof the display element comprise at least 10 unique dose countingindicia.
 18. An inhaler according to claim 12, wherein the dose countingindicia comprise numerals.
 19. An inhaler according to claim 12, whereineach dose counting indicia is representative of a number of dosesdispensed by or remaining in the inhaler.
 20. An inhaler according toclaim 11, wherein the housing further comprises an inner housing memberarranged within the pair of outer housing members.
 21. An inhaleraccording to claim 20, further comprising the medicament dispensingmechanism for opening the blister pockets of the blister pack.
 22. Aninhaler according to claim 21, further comprising the blister pack,wherein each blister pocket contains a measured dose of a dry-powdermedicament.
 23. An inhaler according to claim 21, for deliveringmedicament from a blister pack in the form of a flexible elongate stripcomprising a base sheet having a plurality of recesses spaced along itslength and a cover sheet peelably sealed to the base sheet to define theplurality of blister pockets, wherein the medicament dispensingmechanism comprises means for peeling the cover sheet away from the basesheet of the blister pack.
 24. An inhaler according to claim 23, whereinthe medicament dispensing mechanism comprises means for longitudinallyindexing the blister pack in response to each actuation of themedicament dispensing mechanism, the blister pack being indexed by adistance equal to a pitch between blister pockets, such that eachactuation causes a blister to be brought into registration with the atleast one medicament aperture of the manifold.
 25. An inhaler accordingto claim 24, wherein the means for indexing comprises a driven indexingwheel having recesses adapted to receive the base sheet of the blisterpack, the driven indexing wheel being arranged to turn by apredetermined angle in response to each actuation of the medicamentdispensing mechanism.
 26. An inhaler according to claim 24, furthercomprising a trigger for actuating the medicament dispensing mechanism.27. An inhaler according to claim 23, wherein the medicament dispensingmechanism comprises a driven cover sheet winding wheel for winding up aused portion of the cover sheet.
 28. An inhaler according to claim 27,wherein the cover sheet winding wheel is arranged to apply a tension tothe used portion of the cover sheet, and wherein the medicamentdispensing mechanism further comprises a guide surface for guiding thecover sheet of the unused portion of the blister pack, an end of theguide surface being arranged adjacent to an outer side surface of themanifold and defining a peeling edge, such that, in use, the cover sheetis peeled away from the base sheet at the peeling edge and the usedportion of the cover sheet passes between the peeling edge and the outerside surface of the manifold, and an opened blister pocket moves intoregistration with the at least one medicament aperture of the manifold,wherein the guide surface is defined by the inner housing member, suchthat the manifold and the guide surface are defined by separatecomponents of the inhaler.
 29. An inhaler according to claim 28, whereinthe inner housing member and the pair of outer housing members comprisemeans for locating the inner housing member relative to the pair ofouter housing members.
 30. An inhaler according to claim 29, wherein themeans for locating comprises engagement tabs and recesses formed in theinner housing member and the pair of outer housing members, theengagement tabs and recesses being arranged to engage with each other tofix the location of the inner housing member relative to the pair ofouter housing members.
 31. An inhaler according to claim 27, wherein theinner housing member defines internal transverse walls extending in awidth direction of the blister pack for isolating the used portion ofthe cover sheet from an unused portion of the blister pack.
 32. Aninhaler according to claim 31, wherein the medicament dispensingmechanism further comprises a driven base sheet winding wheel forwinding up the used portion of the base sheet, and wherein the innerhousing member further defines internal transverse walls extending inthe width direction of the blister pack for isolating the used portionof the base sheet from the unused portion of the blister pack.
 33. Aninhaler according to claim 31, wherein the internal transverse walls ofthe inner housing member define separate compartments for accommodatingthe used portion of the cover sheet and the used portion of the basesheet, the separate compartments being arranged to contain loosemedicament.
 34. An inhaler according to claim 33, wherein the internaltransverse walls of the inner housing member further define a separatecompartment for accommodating the unused portion of the blister pack.35. An inhaler according to claim 31, wherein the internal transversewalls extend in a perpendicular direction from a base surface of theinner housing member, the base surface of the inner housing member beingarranged to support a side edge of the unused portion of the blisterpack.
 36. An inhaler according to claim 25, wherein one of the pair ofouter housing members is arranged to support an opposite side edge ofthe unused portion of the blister pack.
 37. An inhaler according toclaim 33, wherein surfaces of the inner housing member and one of thepair of outer housing members are arranged to substantially enclose theunused portion of the blister pack.
 38. An inhaler for deliveringdry-powder medicament to apatient from an open blister pocket of ablister pack, the blister pack having a plurality of blister pocketsspaced apart in a length direction of the pack and each containing ameasured dose of the medicament, the inhaler comprising: a housing forenclosing used and unused portions of the blister pack together with amedicament dispensing mechanism for opening the blister pockets of theblister pack; and a manifold through which air can be drawn in use ofthe inhaler, the manifold comprising an air inlet for receiving externalair, at least one medicament aperture for communicating with an openingpocket of the blister pack to enable entrainment of the medicament byair drawn through the manifold, and an air outlet for delivery of theentrained medicament to the patient, wherein the manifold and a part ofthe housing are provided as a unitary moulded plastics component,wherein the unitary component defines, in use, at least a portion of theouter surface of the inhaler in which the air inlet is arranged, andwherein the manifold comprises at least two medicament aperturesarranged sequentially in an airflow direction of the manifold, a firstmedicament aperture for the flow of air from the manifold into theopened blister pocket and a second medicament aperture for the flow ofthe entrained medicament from the opened blister pocket into themanifold.
 39. An inhaler according to claim 38, wherein the geometry ofthe manifold is adapted to direct air from the air inlet into the openedblister pocket through the first medicament aperture and to direct theentrained medicament from the opened blister pocket into the manifoldthrough the second medicament aperture.
 40. An inhaler according toclaim 39, wherein the geometry of the manifold is so adapted byproviding means for restricting airflow in the manifold between thefirst and second medicament apertures.
 41. An inhaler according to claim40, wherein the means for restricting airflow comprises a localisedreduction in the cross-sectional area of the manifold.
 42. An inhalerfor delivering dry-powder medicament to a patient from an open blisterpocket of a blister pack, the blister pack having a plurality of blisterpockets spaced apart in a length direction of the pack and eachcontaining a measured dose of the medicament, the inhaler comprising: ahousing for enclosing used and unused portions of the blister packtogether with a medicament dispensing mechanism for opening the blisterpockets of the blister pack; and a manifold through which air can bedrawn in use of the inhaler, the manifold comprising an air inlet forreceiving external air, at least one medicament aperture forcommunicating with an opened pocket of the blister pack to enableentrainment of the medicament by air drawn through the manifold, and anair outlet for delivery of the entrained medicament to the patient,wherein the manifold and a part of the housing are provided as a unitarymoulded plastics component, wherein the unitary component defines, inuse, at least a portion of the outer surface of the inhaler in which theair inlet is arranged, wherein the unitary component further defines amouthpiece arranged to receive, in use, the entrained medicament fromthe air outlet of the manifold, and wherein tapered walls of themouthpiece are provided with a plurality of airflow diversion holes, andwherein the airflow diversion holes are in fluid communication with themanifold such that, in use, air from the manifold is drawn through theairflow diversion holes.
 43. An inhaler according to claim 42, whereinthe airflow diversion holes are arranged such that, in use, air is drawnthrough the holes in a direction substantially parallel to a centralaxis of the mouthpiece for preventing excessive transverse spreading ofthe entrained medicament in the mouthpiece.